On the 4 cylinder engine I see the sensor for the rear O2 sensor is roughly below the car in the exhaust pipe were the drivers right foot would be when sitting in the driver's seat. The connector is actually inside the car near the accelerator pedal It is actually labeled as Bank ! sensor 2.
On the V6 the rear O2 sensors are just behind the catalytic converters on the right bank it is just before where the exhaust comes down from the engine and is just about to meet the "y joint" off the exhaust system. Both rear O2 sensors are very near the engine compartment part of the exhaust system. The sensors should set trouble codes for Bank 1 Sensor 2 and or Bank 2 Sensor 2.